1. Field of the Invention
The invention generally relates to transmission brake controls for motor vehicles. More particularly, the invention relates to a transmission brake control assembly that allows a motor vehicle to partially move without fully disengaging the transmission brake.
2. Description of the Related Art
A transmission brake, or trans-brake, is used to lock the transmission preventing the transmission from turning. A transmission brake is normally controlled through an electrical solenoid. The electrical solenoid locks the transmission brake by preventing a driven shaft from rotating. The transmission brake is typically operated using a button-type switch which is under the control of the vehicle operator. Once the transmission brake is enabled, the motor vehicle is prevented from moving until the transmission brake is released.
The transmission brake is a device that is used in various situations, including drag racing events. Once the motor vehicle is positioned on the starting line, the vehicle operator engages the transmission brake, allowing the operator to manipulate the throttle without moving the motor vehicle. The benefit in drag racing is the ability to provide all available power from the internal combustion engine while the motor vehicle is held stationary. The button-type switch used to release the transmission brake releases the motor vehicle to allow it to move within a very short reaction time.
In many applications, it is desirable to allow the motor vehicle to move (creep) under a controlled fashion on the starting line of a drag race track. Drag racing uses a rather complex method of ensuring that the motor vehicle is aligned in the proper position at the starting line by imposing a “pre-stage” position indication and a “staged” position indication. When two motor vehicles which are competing are both “staged” the race may begin at the starting line official's discretion. An operator of a motor vehicle equipped with a transmission brake would normally engage it when he has received the “staged” indication. The “pre-staged” indication is to let the operator know that the motor vehicle is in a pre-set distance from the “staged” position. In many cases, it would be advantageous for the operator to prepare for the start of the race as early as possible from a known position. The current control assemblies for transmission brakes do not, however, provide for any such movement of the motor vehicle as the transmission brake control assemblies currently are digital, i.e., either on or off.